This invention relates generally to a liquid sampling device, and more particularly to an improved method and apparatus for monitoring the concentration of contaminants, including volatile organic compounds, in groundwater. Various devices exist for sampling a liquid. A known type of passive, multi-layer sampling device which is used to extract groundwater samples is comprised of a rod (or connector rods) with apertures at specific intervals to accommodate dialysis cells.
U.S. Pat. No. 5,454,275 to Kabis discloses a groundwater sampler which makes use of pressure differentials that result during sampling. U.S. Pat. No. 5,147,561 to Burge et al. teaches a sampling device containing a stripping chamber for stripping a groundwater sample of its volatile components at or near the point of collection. U.S. Pat. No. 4,078,433 to McCabe, Jr. et al. discloses a liquid sampling device comprising a length of pipe having a cap screwed onto each end thereof. The upper cap has an aperture for admitting the liquid to be sampled into the pipe. Despite the prior art devices, there is a need for improvement in the art of groundwater sampling. The use of thin semipermeable membrane materials in water sampling devices presents certain problems due to the very sensitive nature of the membrane. Such membrane are easily damaged in the course of use during placement in a well and removal.